19-12-2021, 01:44 PM
(19-12-2021, 12:57 PM)Kalee20 Wrote: I've seen one of these amplifiers - printed-circuit board but on a metal baseplate the same size as the previous 606 amplifier's chassis.
I'm rather interested if a circuit diagram comes to light, how the sound exciter lamp is powered. B & H were fond of using a 6V6 as an oscillator and driving the lamp from HF AC (the light source needs to be steady and ripple-free, so 50/60Hz AC is no good). Whether with the extra space, as a result of the miniature valves, allowed use of a metal rectifier and smoothing cap, to run the lamp from DC, I'm curious to see!
The whole thing is weird. They run on AC or DC but I have yet to find a rectifier! I suspect that one of what I thought were all UL84 is actually a PY82 or similar, the 4 valves are all the same size.
There is an EF86 next to the photocell, the exciter lamp was very close so I would guess that the EF86 is the "modern" equivalent of the 6V6. There are a couple of circuit diagrams with three 6V6 valves which may be almost the same as this one.
Watch this space, its too cold in the workshop today, if I could find it in the fog!
Boater Sam.
